The present invention relates, in general, to the field of Fibre Channel switching technology. More particularly, the present invention relates to a port module that is adapted to receive a 10 gigabit-per-second fiber link for use in a Fibre Channel switching environment.
Fibre Channel is a high performance, serial interconnect standard designed for bi-directional, point-to-point communications between servers, storage systems, workstations, switches, and hubs. It offers a variety of benefits over other link-level protocols, including efficiency and high performance, scalability, simplicity, ease of use and installation, and support for popular high level protocols.
Fibre Channel employs a topology known as a “fabric” to establish connections between nodes. A fabric is a network of switches for interconnecting a plurality of devices without restriction as to the manner in which the switch can be arranged. A fabric can include a mixture of point-to-point and arbitrated loop topologies.
In Fibre Channel, a channel is established between two nodes where the channel's primary task is to transport data from one point to another at high speed with low latency. The Fibre Channel switch provides flexible circuit/packet switched topology by establishing multiple simultaneous point-to-point connections. Because these connections are managed by the switches or “fabric elements” rather than the connected end devices or “nodes”, fabric traffic management is greatly simplified from the perspective of the device.
The basic element of a fabric is a switch. In a fibre channel system, data is transported in frames, where each frame has a header identifying, among other things, a destination node. The destination identification is referred to as a “DID”. A switch comprises a plurality of ports that transmit and receive data frames from an external link. The port is implemented by circuitry that receives data from the external link, buffers data as needed, and preferably performs some analysis to ensure integrity of the received data and use header information, such as the DID to process the received frame within the switch.
A switch also includes mechanism such as a crossbar matrix or the like to internally couple each port on the switch to another port on the switch so that frames received on one port (e.g., a receive or RX port) can be communicated to another port (e.g., a transmit or TX port). A switch also includes data processing mechanisms for analyzing the received frame to determine the appropriate TX port that will reach the node specified by the frame's DID. In any given switch, the port electronics have a maximum data rate determined by the hardware components. Typically the port electronics will support data rates lower than the maximum data rate, but not higher.
As Fibre Channel technology advances, an increase in the data transmission speed of the Fibre Channel links becomes increasingly desirable. However, in many cases, the existing hardware is incompatible with advances in the overall speed of the network. As a result, it becomes necessary to either replace the existing hardware, a costly alternative, or gradually transition to the new technology utilizing add-ons that operate to merge new technology and existing technology. If properly configured, add-ons, such as plug-in adapters or the like, allow combinations of current architecture and technological advances with only incremental modifications.
Currently, universal port modules provide a 1 Gb/s and a 2 Gb/s data rate for Fibre Channel switching systems. However, a new Fibre Channel standard exists that discloses an increase to a 10 Gb/s data rate. Most existing architectures are not designed to handle and effectively utilize the increase in data rate without significant modifications and upgrades to hardware components since most systems are designed to handle lower than a maximum data rate but not a higher than a maximum data rate. Hence, there is a need for a port module for use with existing Fibre Channel switching architecture that is capable of utilizing a 10 Gb/s data rate in accordance with the Fibre Channel standard.